Open side stringing sheave



Nov. 2 8, 1961 G. A. PETERSEN OPEN SIDE STRINGING SHEAVE Filed Jan. 12,1959 INVENTOR. Gerald A. Petersen United States Patent f 3,010,700 p lOPEN SIDE STRINGING SHEAVE I Gerald A. Petersen, Saratoga, Calif.Petersen Engineering CoL, 461 Kifer Road, Santa Clara, Calif.)

Filed Jan. 12, 1959,"Ser. No. 786,430 4 Claims. (Cl. 254*1343) pendingfrom towers and, accordingly, a sheave is in stalledat eachcf the towersspaced along the line. To facilitate the stringingoperations, in thefirst'instance, a steel cable is passed through the sheaves andconnected to the aluminum or copper conductor. The cable is pulled undertension and tends to'rot'ate as it is pulled in. To reduce rotation ofthe steel pulling line, swivels are frequently installed adjacent eachend of the pulling line and sometimes swivels are installed alongthe'length of the line. Visual observation of the swivels as thestringing operation proceeds shows that one-half of the swivel spinsrapidly when tensions are heavy. Since the sheave is made of alightweight material, such'as' aluminum or magnesium, the rotating steelpulling line'tends to chew up the bottom of the groove in the sheave andthus to damage the sheave. Scoring of the groove re sults inconsequential damage to the conductor when it.

follows the steel pulling line through the sheave because the roughsurfaces produced by the steel pulling line on the sheave martheconductor, and this isaserious prob- .lem in the construction oftransmission lines.

In accordance with the present invention, the groove in the sheave ispartly lined with a resilient substance such as neoprene which will notscuff up by action'of the steel pulling line and, hence, will notsubsequently damage the conductor. The resilient insert wears muchlonger than aluminum or magnesium;

Insertion of rubber in the entire groove of the sheave creates a problemafter the bottom of the groove is worn because the cost ofrevulcanization is prohibitive.

Forming the liner merely in the bottomof the groove is unsatisfactorybecause rotation of the pulling line under heavy tension causes it toclimb up the side of the sheave groove and, if it climbs higher than thelimit of the lining, it damages the sheave itself. Accordingly, thepresent-invention employs a-resilient' insert which extends partway upthe side of the'groo've so that the steel pulling line will not damagethe groove of the sheave and yet the width of the insert is not so greatto make revulcanization of a new insert in the sheave 'unduly expensive.The extent of the insert up the side of the groove is about equal totheelevation of the center of the largest size conductor used in the sheaveand'about twice the diameter of the pulling line employed;

3,010,700 Patented Nov. 28', 1961 invention reduces the likelihood offlattening the conductor, because of the fact that the conductor ispulled over a resilient surface. I

Another feature of the invention is the employment of a conductivematerial in the resilient liner of the sheave so that the accumulationof staticelectricity is eliminated.

Other objects of the present invention will become apparent upon readingthe following specification, and'referring to the accompanying drawingsin which similar charactersof reference represent" corresponding partsin each of the several views.

In the drawings:

FIG. 1 is a side elevation of the sheave.

FIG. 2 is ariend elevation.

FIG. 3 is a vertical sectional view taken substantially along line 3-3of FIG. 1.

FIG. 4 is an enlarged fragmentary sectionalview of the groove of thesheave and liner showing in dotted lines the steel pulling cable and theconductor.

FIG. 5 is afragmentary enlarged sectional view of a portionof theconductor retainer.

The stringing sheave, which is the subjectof this invention, employspulley 11 preferably of a lightweight material such as aluminum ormagnesium rotatably mounted on the lower end of bracket 13. The upperend of bracket 13 isprovided with an attachment device 14 hereinafterdescribed in detail, which may be attached to the lower end of aninsulator 17 or other means employed to'suspend a cable from a powerpole cross arm.. The sheave may be grounded by wire 16 attachedtobracket 13 and by a clip 15 to the cross arm, or the sheave may bedirectly connected to the cross arm instead of the insulator.

When the sheave is installed in position, a steel caole 21 or pullingline of relatively small diameter is first suspended by the sheave and,after having been suspended, is pulled through the sheave. The end ofcable 21 is connected by means forming no part of this invention to oneend of the conductor 22, which is ordinarily copper or aluminum and isof considerably greater diameter than steel cable 21. After conductor 22has been installed in position, it is connected to insulator 17 and thestringing sheave is removed. Accordingly, pulley 11 is formed with aperipheral U-shaped groove 23 having a rounded arcuate bottom 24 andsides 26. The distance between sides 26 and the radius of curvature ofbottom 24 must be sufiicient to accommodate the largest diameterconductor 22 to be usedwith the sheave.

By reason of the fact that pulley 11 is formed of a relatively softmateriahsuch as aluminum or magnesium and the pulling cable 21 of a hardmaterial, such as steel, bottom 24 of groove 23 tends to wear rapidly,requi'ring replacement of pulley 21. A lubricant may be used to reducethe wear, but this is not satis'factory'be cause of the severe action ofcable 21'. The present in A further feature of the invention is the factthat the When a vention has as one of its principal features theprovision of an annular liner 27 inserted in a recess 28 in the bottom24' of groove 23L The exterior surface 29 of liner 27 has a curvaturesimilar to the curvature of bottom 24, but is raised above bottom 24 soas to cover corner edges 31 of recess 28 and hence protect therelatively soft power cable 22 from abrasion. Recess 28 is shallow andhas a width approximately twice the diameter of the largest sizestringing cable 21 which is intended to be employed with the'sheave.

A preferred material for the fabrication of liner 271s electricallyconductive neoprene (synthetic rubber), which is a resilientmaterialwhich withstands the abrasion of pulling cable 21 and yet will conductelectricity to the pulley 11 and thence to ground, thereby preventingthe building up of static electricity. When such conducis substantiallycontinuous.

tive neoprene is employed, then the use of a conductive lubricant isobviated. As the stringing cable 21 is drawn through the sheave, itrides upon the exterior surface 29 of insert 27. Insert 27 is moreresistant to abrasion than are sides 26 and bottom 24 of pulley 1.1, andhence wear is reduced. Further, liner 27 may be replaced and a new linervulcanized in place when required.

Bracket 13 comprises an enlongated, thin vertical web 36 formed with aplurality of apertures 37, 38, 39 to facilitate handling of the sheaveto reduce weight and further, when desired, to receive the rope used tohoist the sheave into place. For similar usage, a plurality of ears 41formed with apertures 42, similar in shape to teacup handles, areattached to the web 36 inwardly of the apertures 37, 38 thereof andapproximately at the level of the top of the pulley 11. When a rope isslung through the apertures 42 in one or both of the ears, the raisingof the sheave with cable 21 installed therein is facilitated and thetendency of the cable to twist out of alignment is to a large extenteliminated.

The lower end of the web 26 is formed with a circular abutment 46 havinga stepped outwardly extending boss 47. The face of hub 48 of pulley 11adjacent abutment 46 is formed with a recess 49 having a shoulder 51 atits innermost end. Double ball bearing 54 fits within recess 49 and isheld in place against shoulder 51 by snap ring retainer 52. The innerrace of the bearing 54 fits over boss 47 and is held in place by snapring retainer 53. Cover plate 56 covers over the open end of recess 49and is secured in place on hub 48 by screws 57, the heads of which arecountersunk into the face of plate 56 and the shanks of which arereceived in tapped holes 58 in hub 48. It will be noted that this methodof mounting the pulley on the bracket insures that there are no exposedbolt heads or nuts which may snag. This feature of construction is ofconsiderable advantage in the use of the sheave.

To prevent the cable 21 or conductor 22 from binding between the bracketand the pulley, a curved shoulder 61 is formed on the'inner surface ofweb 36 at the upper end of the pulley 11, the curvature of the shoulder61 merging with the rim edge 62 of the pulley.

To facilitate installation of the conductor in the sheave, a largeopening 63 is provided in the bracket 13 above the pulley. This featureis of particular advantage, in that it enables a conductor splice topass over the pulley and through the bracket. To retain the conductor inplace, a keeper 66 is provided. The keeper 66 comprises a. closuremember 67 having a pair of upstanding ears 68. The bracket is cut away,as indicated by reference numerals 69, 69 on either side thereof toreceive the cars 63, so that the width of the bracket, with the earsinstalled, A pin 71 is inserted through the ears 6S and through thetongue 72 in the bracket between the recesses 69 to provide a pivot forthe keeper. A short length of coil spring 73 is wrapped around pivot pin71 and fixed to one of the cars 68 and to the tongue 72 and functions tobias the keeper to closed position. Here again, it will be noted thatthere is no exposed nut or bolt which may snag. The keeper below pivot71 is formed concavo-convex in end elevation. The convex externalsurface 76 of the keeper merges with the upper edge of the outer rim 62of the pulley 11 and, hence, when a conductor is brought to bear againstsaid surface 76, the keeper is pivoted inwardly to permit the conductorto move into the opening 63 and thence into the groove 23 in the pulley11. The concave inner surface 77 of the keeper 66 merges with thecurvature of the groove 23 in the pulley, and it further will beobserved that the lower tip 77 of the keeper is in close proximity tothe rim 62 of the pulley.

The upper end of the hanger is cut away as indicated by numeral 81 andformed with a pair of spaced upwardly extending lugs 82 parallel to web36 and reinforced with gussets 83 merging into the cut-away surface 81.A flat horizontal shoulder 84 is provided on the upper edge of the lugs82. A sockeye fitting 14 having a downwardly projecting tongue 86 fitsbetween the lugs 82 and is secured in place by bolt and nut 87-88passing through aligned apertures in the lugs 82 and tongue 86. Thesockeye fitting 14 has a shoulder which fits against shoulder 84 on thetop of the lugs 82 to prevent pivoting of the sockeye fitting from itsproper position. The construction of the sockeye fitting 14 is wellunderstood in this art and comprises a member having a recess 91extending horizontally inwardly from one surface thereof, the recessmerging with a vertically extending recess 92 of lesser depth, whichvertical recess 92 extends upwardly to the top edge of the fitting. Itwill be understood that other fittings may be employed.

In use, sheaves are hoisted by a rope passed through handle 41 oraperture 37, 38 or 39' in web 36 to the cross arms of each tower alongthe line. A pulling line 21 may be inserted through keeper 66 intogroove 23 either before or after the sheaves are hoisted. The sheave maybe attached to insulator 17 by means of fitting 14 or other convenientmeans and may be grounded by cable 16. The pulling line is attached toconductor 22 and wound in, the conductor being pulled through eachsheave along the line. As the pulling line 21 is wound in it tends torotate, but abrasion of the sheave is resisted by insert 27.Accumulation of static electricity is prevented by reason of theconductive resilient material of which insert 27 is constructed. Afterthe conductor has been strung, it is removed through keeper 66 andattached to insulator 17, the sheave being lowered to the ground.Whenever liner 27 is worn out, a new liner may be vulcanized in recess28.

Although the foregoing invention has been described in some detail, byway of illustration and example for purposes of clarity ofunderstanding, it is understood that certain changes and modificationsmay be practiced Within the spirit of the invention and scope of theappended claims.

I claim:

1. A stringing sheave comprising a pulley formed with a relatively deepperipheral groove, and means for rotatably mounting said pulley, saidpulley being formed with a shallow circumferential arcuate recess aroundthe bottom of said groove and partially up the sides of said groove, andan insert formed of an electrically conductive resilient material insaid recess and extending around the bottom of said groove.

2. A stringing sheave comprising a pulley formed with a relatively deepperipheral groove, and means for rotatably mounting said pulley, saidpulley being formed with a shallow circumferential recess around thebottom of said groove, the upper marginal edges of said groove 1 beingrelatively sharp, and an insert formed of an electrically conductiveresilient material in said recess and extending around the bottom ofsaid groove and partially up the sides of said groove, the upper surfaceof said insert along its side edges being raised above the bottom ofsaid groove to protect said edge of said groove adjacent said recessfromcontact with a cable strung by said sheave.

3. A stringing sheave comprising a pulley having a hub and formed with arelatively deep peripheral groove, and a hanger for said pulley, saidhanger having an attachment device above the axis of said pulley, a webdepending from said attachment device displaced laterally from saidpulley to one side of said pulley, a boss on said web extending throughand concentric with the axis of said pulley, bearing means mounting saidhub on said boss positioned directly below said attachment device, saidpulley being formed with a shallow circumferential arcu ate recessextending around the bottom of said groove and partially up the sides ofsaid groove, and an insert formed of an electrically conductiveresilient material in said recess and extending around the bottom ofsaid groove.

4. A stringing sheave comprising a pulley having a hub and formed with arelatively deep peripheral groove, and a hanger for said pulley, saidhanger having an attachment device above the axis of said pulley, a webdepending from said attachment device displaced laterally from saidpulley to one side of said pulley, a boss on said web extending throughand concentric with the axis of said pulley, bearing means mounting saidhub on said boss positioned directly below said attachment device, saidhanger being formed with an enlarged, substantially arenate, openingbelow said attachment device and above said pulley, the portion of saidhanger defining said opening adjacent said pulley overhanging the rim ofsaid pulley adjacent said web, a keeper depending from said hanger andextending to a point adjacent the top edge of said pulley opposite saidweb, said keeperbeing convex on the outside and concave on the inside,the inside surface of said keeper merging with the walls of said openingand the lower end of said keeper extending to overhang the rim of saidpulley adjacent said keeper, means mounting 20 said keeper for pivotalmovement inwardly into said enlarged opening, a pair of ears in theshape of teacup handles projecting out from said web parallel to saidsheave and above said pulley, said pulley being formed with a shallowcircumferential recess around the bottom of said groove, the uppermarginal edges of said groove being relatively sharp, and an insertformed of an electrically conductive resilient material in saidrecessand extending around the bottom of said groove and partially upthe sides of said groove, the upper surface of said insert along itsside edges being raised above the bottom of said groove to protect saidedge of said groove adjacent said recess from contact with a cablestrung by said sheave.

References Cited in the file of this patent UNITED STATES PATENTS D.184,880 Lindsey Apr. 14, 1959 1,780,627 Muller Nov. 4, 1930 1,944,426Greening Jan. 23, 1934 2,197,698 Lamberth Apr. 16, 1940 2,524,509 BarneyOct. 3, 1950 2,649,282 Fate Aug. 18, 1953 2,879,452 Page Mar. 24, 1959FOREIGN PATENTS Great Britain Dec. 1, 1921

